<!DOCTYPE html>
<meta charset="utf-8">
<title>Opener to an existing window</title>
<body></body>
<script>
  window.onmessage = (event) => {
    window.onmessage = (event) => parent.postMessage(event.data, "*");
    const { url, token } = event.data;
    window.open('', token);
    window.open(url, token);
  };
</script>
